The ASAP Electrical replacement navigation lamp bulbs are suitable for Perko, Vetus, Aqua Signal, Hella and many other makes of navigation lights. This bulb has a Small Bayonet Cap (BAY15d) fitting, which consists of a 15mm two contact base and a bayonet fitting with offset pins. The incandescent light bulb is suitable for 12 volt electrical systems and is rated 10 watts.